U.S. patent application number 12/294586 was filed with the patent office on 2010-01-07 for membrane element, membrane unit, and multi-deck membrane unit.
Invention is credited to Hiromitsu Kanamori, Hiroshi Matsumoto, Yoshifumi Odaka, Toshitsugu Onoe, Kenji Sakai.
Application Number | 20100000935 12/294586 |
Document ID | / |
Family ID | 38624757 |
Filed Date | 2010-01-07 |
United States Patent
Application |
20100000935 |
Kind Code |
A1 |
Sakai; Kenji ; et
al. |
January 7, 2010 |
MEMBRANE ELEMENT, MEMBRANE UNIT, AND MULTI-DECK MEMBRANE UNIT
Abstract
Provided are membrane elements and membrane units capable of
easily forming a space part surrounded with a frame body above the
membrane elements regardless of the number of the membrane
elements. That is, the membrane elements are membrane elements each
comprising filtering membranes on both surfaces of a plate-like
supporting plate, wherein spacer parts are formed in both side
parts for keeping the membrane face distance to adjacent membrane
elements being prescribed intervals, and the spacer parts have
through bolt insertion holes and are extended upward from the upper
end part of the supporting plate. The membrane units are configured
by arranging a plurality of the membrane elements in such a manner
that the channel parts formed in the spacer parts are brought into
contact with each other, seal panels are installed in the outermost
parts of the arranged membrane elements, and a frame body is formed
by surrounding the space above the filtering membranes by the
spacer parts and the seal panels.
Inventors: |
Sakai; Kenji; (Otsu-shi,
JP) ; Kanamori; Hiromitsu; (Otsu-shi, JP) ;
Odaka; Yoshifumi; (Otsu-shi, JP) ; Onoe;
Toshitsugu; (Otsu-shi, JP) ; Matsumoto; Hiroshi;
(Otsu-shi, JP) |
Correspondence
Address: |
RATNERPRESTIA
P.O. BOX 980
VALLEY FORGE
PA
19482
US
|
Family ID: |
38624757 |
Appl. No.: |
12/294586 |
Filed: |
February 6, 2007 |
PCT Filed: |
February 6, 2007 |
PCT NO: |
PCT/JP2007/051957 |
371 Date: |
March 16, 2009 |
Current U.S.
Class: |
210/455 |
Current CPC
Class: |
B01D 2313/06 20130101;
B01D 2315/06 20130101; B01D 2313/02 20130101; B01D 2313/26
20130101; B01D 63/082 20130101; B01D 2313/12 20130101; Y02W 10/15
20150501; Y02W 10/10 20150501; C02F 3/1273 20130101 |
Class at
Publication: |
210/455 |
International
Class: |
B01D 69/06 20060101
B01D069/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2006 |
JP |
2006-085201 |
Apr 21, 2006 |
JP |
2006-117580 |
Apr 21, 2006 |
JP |
2006-117581 |
Claims
1. A membrane element comprising filtering membranes on both
surfaces of a plate-like supporting plate, wherein spacer parts are
disposed at both side parts of the membrane element for keeping a
prescribed distance to a surface of an adjacent membrane element,
wherein the spacer parts have through bolt insertion holes and are
extended upward from an upper end part of the supporting plate, and
the through bolt insertion holes are U-shape holes opened to a side
face of the membrane element and penetrating from a front surface
toward a rear surface of the membrane element.
2. The membrane element according to claim 1, wherein a channel
part having a through hole for forming a water collecting pipe is
disposed in an upper part of the spacer part and the through hole
in the channel part and an inside of a filtered water chamber
formed by the filtering membranes disposed on both surfaces of the
supporting plate are in fluid communication.
3. The membrane element according to claim 1, wherein a projection
part for fitting and a reception part for fitting are formed in the
spacer part for positioning with an adjacent membrane element.
4. (canceled)
5. A membrane unit comprising a plurality of membrane elements
according to claim 1 arranged in such a manner that the spacer
parts are brought into contact with each other, seal panels are
disposed at outermost parts of the plurality of membrane elements,
and a frame body surrounding a space above the filtering membranes
is formed by the spacer parts and the seal panels.
6. A membrane unit comprising a plurality of membrane elements
according to claim 1 arranged in such a manner that the spacer
parts are brought into contact with each other, and seal panels
having through bolt insertion holes are disposed at outermost parts
of the plurality of membrane elements, wherein the membrane
elements and the seal panels are united by through bolts inserted
into the U-shape holes of the membrane elements and the through
bolt insertion holes of the seal panels.
7. A membrane unit comprising a plurality of membrane elements
according to claim 2 arranged in such a manner that the channel
parts formed in the spacer parts are brought into contact with each
other, seal panels are disposed at outermost parts of the plurality
of membrane elements, a frame body surrounding a space above the
filtering membranes is formed by the spacer parts and the seal
panels, and a water collecting pipe is formed by bringing a
plurality of the channel parts into contact with one another.
8. A multi-deck membrane unit comprising the membrane unit
apparatus according to claim 5 layered vertically in multi-decks.
Description
TECHNICAL FIELD
[0001] The invention relates to a membrane unit and a membrane
element suitable to be used as a membrane filtration apparatus
particularly for wastewater treatment and water purification
treatment.
BACKGROUND ART
[0002] As a membrane separation technique to be applied for
wastewater treatment has been known a technique of obtaining
membrane-filtered water by immersing a membrane unit in which a
plurality of membrane elements are arranged and inserted in a
treatment tank filled with wastewater such as activated sludge and
by suctioning the filtered water side of the membrane unit by a
pump, or discharging water based on the water level difference just
like a siphon.
[0003] In the case of activated sludge process, to propagate
aerobic microorganism in the treatment tank, air diffusion to the
tank is required. If an apparatus for air diffusion is installed
down below a membrane unit, the gas-liquid mixing flow by the air
diffusion can ascend in the membrane unit and scrape contamination
of the membrane surfaces (membrane faces). As a result,
solid-liquid separation can be carried out while the cleaning of
the membrane surface is carried out, and thus the membrane
filtration operation can be carried out at a low cost.
[0004] At that time, if the velocity of the gas-liquid mixing flow
for scraping the membrane surfaces is high, stable operation can be
continued. As means for increasing the velocity of the gas-liquid
mixing flow, as shown in FIG. 12, has been proposed a method for
efficiently generating ascending water current by installing a
box-like upper housing 84 on an upper part of a box-like housing 83
containing membrane elements 71 composing a membrane unit (see
Patent Document 1). Further, as shown in FIG. 13, it has also been
proposed to use air efficiently by mounting another membrane unit
82' on a box-like upper housing 84 mounted on a membrane unit 82
and supplying the gas-liquid mixing flow with increased velocity to
the upper membrane unit 82' (see Patent Document 2). Furthermore,
to increase the cleaning power by making the gas-liquid mixing flow
high speed, it is also preferable to increase the quantity of air
to be diffused from the lower side of a membrane unit.
[0005] Further, in order to carry out membrane filtration operation
stable, it is also important to keep the intervals of raw water
channels formed between respective membrane elements constant, and
for example, a membrane unit obtained by setting a plurality of
membrane elements having projected parts (spacer parts) in the
circumferential rim parts in a casing while bringing the spacer
parts of adjacent membrane elements into contact with each other
has been also disclosed (see Patent Document 3). Accordingly, a
gas-liquid mixing flow can be evenly sent close to the membrane
surface of each membrane element, and the membrane surface of each
membrane element can be washed evenly.
[0006] However, in the above-mentioned techniques described in
Patent Documents 1 and 2, in order to increase the velocity of the
gas-liquid mixing flow, it is required to install the housing,
being an additional member, on the upper parts of membrane element.
As the membrane unit, since the membrane elements are contained in
a housing 83 with a size corresponding to a desired number of
membrane elements, it is also required to adjust the size of the
housing 84 depending on the size of the housing 83. That is, it is
required to produce upper housings 84 with various sizes depending
on the number of membrane elements, and thus there is a problem
regarding the efficiency in terms of the apparatus production.
Further, if the velocity of the gas-liquid mixing flow is further
increased, the pulsation becomes intense and therefore a preferable
state for removing contaminations from the filtering membrane
surfaces 71 is produced. On the other hand, an excess load is
applied to the membrane elements 71, and therefore, the
displacement of membrane elements tends to occur. Furthermore, a
supporting plate bends considerably and tends to deform, the spacer
parts move slightly, and thus a problem of causing wear tends to
occur.
[0007] The method of increasing an air amount is a preferable for
removing contaminations of the filtering membrane surface because
of a strenuous pulsation. On the other hand, since an excess load
is applied to the supporting plate of the membrane element, the
displacement of the membrane elements tends to occur. Furthermore,
the supporting plate bends considerably and tends to deform, the
spacer parts move slightly, and thus a problem of causing wear
tends to occur. Furthermore, in a case where the membrane unit
apparatus in which intervals of the raw water channels are kept
constant by bringing the above-mentioned spacer parts into contact
with each other, there is a problem that the intervals of the raw
water channels of membrane faces are easily fluctuated due to
vibration of the membrane elements generated during the
operation.
[0008] In order to prevent the displacement of the membrane
elements even if a load is applied due to the high velocity
gas-liquid mixing flow in an immersion tank and keep the intervals
of the membrane surfaces constant, it has been also proposed that a
membrane unit is assembled by arranging a plurality of membrane
elements having spacer parts in both right and left sides of
supporting plates in such a manner that the spacer parts are
brought into contact with each other and uniting the membrane
elements by inserting through bolts into holes formed in the
supporting plates (see Patent Document 4). In the case of this
membrane unit, in order to prevent slight movement wear in the
contacting spacer parts, the through bolts 45 have to be fastened
to make the fastening force of the contacting spacer parts higher
than the force applied to the supporting plates, and then the
slight movement of the spacer parts can be prevented.
[0009] However, with the membrane unit structure described in that
document, if the through bolts are fastened firmly, particularly
the supporting plates themselves of membrane elements at the
outside positions bends considerably to result in a problem that
the supporting plates are broken or the spacer parts cannot be
brought into contact since the fastening positions of the spacer
parts and the through bolts are apart, and the slight movement wear
is further promoted.
Patent Document 1: Japanese Patent No. 3290577
Patent Document 2: Japanese Patent No. 3667131
Patent Document 3: Japanese Utility Model Application Laid-Open No.
6-60427
Patent Document 4: Japanese Patent Application Laid-Open (JP-A) No.
8-89765
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0010] An object of the invention is to solve the above-mentioned
problems and provide a membrane element, a membrane unit, and a
multi-deck membrane unit with which a space part surrounded with a
frame body can easily be installed above the membrane element
regardless of a number of the membrane element and wear of spacer
parts can be suppressed. Another object of the invention is to
provide a membrane element, a membrane unit, and a multi-deck
membrane unit with which air supplied from the lower part of the
membrane element can efficiently be utilized and the efficiency in
terms of an apparatus production can be improved.
Means for Solving the Problems
[0011] In order to accomplish the objects, the invention includes
the following configuration. That is:
(1) a membrane element comprising filtering membranes on both
surfaces of a plate-like supporting plate, wherein spacer parts are
formed at both side parts of the membrane element for keeping
prescribed distance to the surface of an adjacent membrane element,
and the spacer parts have through bolt insertion holes and are
extended upward from the upper end part of the supporting plate;
(2) The membrane element according to (1), wherein the through bolt
insertion holes are U-shape holes opened to the side face of the
membrane element and penetrating form the front surface to the rear
surface of the membrane element; (3) The membrane element according
to (1) or (2), wherein projection part for fitting and reception
part for fitting are formed in the spacer part for positioning with
an adjacent membrane element; (4) The membrane element according to
any one of (1) to (3), wherein a channel part having a through hole
for forming a water collecting pipe is formed in the upper part of
the spacer part and the through hole in the channel part and the
inside of a filtered water chamber formed by the filtering
membranes disposed on both surfaces of the supporting plate are
communicated; (5) A membrane unit having a plurality of membrane
elements according to any one of (1) to (4) arranged in such a
manner that the spacer parts are brought into contact with each
other, seal panels are installed to outermost parts of the arranged
membrane elements, and a frame body surrounding the space above the
filtering membranes is formed by the spacer parts and the seal
panels; (6) A membrane unit comprising a plurality of membrane
elements according to (2) arranged in such a manner that the spacer
parts are brought into contact with each other, and seal panels
having through bolt insertion holes are installed to the outermost
parts of the arranged membrane elements, wherein the membrane
elements and the seal panels are united by inserting through bolts
into the U-shape holes of the membrane elements and the through
bolt insertion holes of the seal panels; (7) A membrane unit
comprising a plurality of membrane elements according to (4)
arranged in such a manner that the channel parts formed in the
spacer parts are brought into contact with each other, seal panels
are installed to the outermost parts of the arranged membrane
elements, a frame body surrounding the space above the filtering
membranes is formed by the spacer parts and the seal panels, and a
water collecting pipe is formed by bringing a plurality of the
channel parts into contact with one another; (8) A multi-deck
membrane unit comprising the membrane unit apparatus according to
any one of (5) to (7) layered vertically in multi-decks.
[0012] In this invention, phrases such as "both side parts", "upper
end part", "above", "side face", "outermost part" and the like are
determined on the basis of the state at the time of use.
EFFECTS OF THE INVENTION
[0013] Since the spacer parts in both right and left sides are
extended above the upper end part of the supporting plate, a
plurality of the membrane elements of the invention can be arranged
in such a manner that the distances of raw water channels to be
formed between the respective membrane elements are kept constant
by bringing the spacer parts into contact with one another; and
further, a membrane unit without requiring an additional housing
and a frame body surrounding the space above the filtering
membranes can be formed by bringing the seal panels into contact
with one another. According to the invention, regardless of the
number of the membrane elements and the size of the membrane units,
a space can reliably be kept above the membrane elements.
Accordingly, air supplied from the lower part of the membrane units
can be efficiently utilized for scraping the contaminations on the
membrane surfaces (membrane faces) and stable membrane filtration
operation is made possible. Further, without installing an upper
housing according to prior arts, the membrane unit can be easily
layered in multi-decks and it is advantageous in terms of the cost,
and the space shape between upper and lower decks is always kept
constant and controlled gas-liquid mixing flow can be efficiently
utilized. In addition, the vibration of spacer parts due to
pulsation is suppressed and wear is decreased by inserting through
bolts into the through bolt insertion holes of the spacer parts and
fastening a plurality of the membrane elements. In this case, the
through bolts do not interrupt the gas-liquid mixing flow.
[0014] In the case where holes for through bolt insertion penetrate
from the front surface to the rear surfaces of membrane elements
and are U-shape holes opened to the side face of the membrane
elements, through bolts can be easily inserted even in that state
that several tens to a hundred and several tens of the membrane
elements are layered. In the case where the projection part for
fitting and reception part for fitting for positioning with an
adjacent membrane element are formed in the spacer parts, the
membrane elements can be easily and evenly layered. Further, in the
case of membrane elements having channel parts in the upper parts
of the spacer parts, the membrane unit is configured by arranging a
plurality of the membrane elements while bringing the channel parts
into contact with one another and also bringing the seal panels
into contact with one another, so that the water collecting pipe
for taking filtered water out can be formed in the upper part of
the membrane unit. As a result, a tube for taking out filtered
water is not necessary and thus the membrane unit can be easily
multi-layered without particular work (e.g. formation of through
holes for leading a tube to the outside of a module) of the wall
parts forming the space parts above the membrane elements.
BRIEF DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a schematic perspective view showing one
embodiment of a membrane element of the invention and a drawing
showing the state before installation of filtering membranes.
[0016] FIG. 2 is a schematic perspective view showing one
embodiment of a membrane module produced by combining a membrane
unit using the membrane element shown in FIG. 1 with an air
diffuser.
[0017] FIG. 3 is a schematic top view showing the upper face of the
membrane unit shown in FIG. 2.
[0018] FIG. 4 is a schematic perspective view showing another
embodiment of a membrane element of the invention and showing the
state before installation of filtering membranes.
[0019] FIG. 5 is a partial cross-sectional view schematically
showing magnified projection parts for fitting and reception parts
for fitting formed in a spacer part.
[0020] FIG. 6 is a schematic drawing of a membrane element having
channel parts in the upper part (extended part) of a spacer
part.
[0021] FIG. 7 is a schematic perspective view showing one
embodiment of a membrane module produced by combining a membrane
unit using the membrane element shown in FIG. 6 with an air
diffuser.
[0022] FIG. 8 is a schematic drawing showing an integration method
of the membrane elements and the seal panels.
[0023] FIG. 9 is a schematic perspective view showing one
embodiment of a membrane module produced by layering the membrane
unit shown in FIG. 7 in two decks.
[0024] FIG. 10 is a schematic cross-sectional view of the membrane
module shown in FIG. 9.
[0025] FIG. 11 is a schematic cross-sectional view schematically
showing a water treatment apparatus using the membrane unit of the
invention.
[0026] FIG. 12 is a schematic cross-sectional view schematically
showing one example of conventional membrane modules.
[0027] FIG. 13 is a schematic cross-sectional view schematically
showing another example of conventional membrane modules.
EXPLANATION OF SYMBOLS
[0028] 1. element [0029] 11. filtering membrane [0030] 12.
supporting plate [0031] 13. spacer part [0032] 14. through bolt
insertion hole [0033] 15. extended part (upward extended part of
spacer part) [0034] 16. collecting groove [0035] 17. filtered water
outlet 18. communicating hole [0036] 21. projection for fitting
[0037] 22. reception for fitting [0038] 23. rib [0039] 31. channel
part [0040] 32. through hole for forming a water collecting pipe
[0041] 41. membrane module [0042] 42. membrane unit [0043] 43.
stand [0044] 44. air diffuser [0045] 45. seal panel [0046] 46.
through bolt [0047] 47. lower frame body [0048] 48. frame body
[0049] 49. space part [0050] 50. nut [0051] 51. raw water channel
[0052] 52. hole part [0053] 53. collecting cap [0054] 61. water to
be treated [0055] 62. air supply pipe [0056] 63. treatment tank
[0057] 64. suction pump [0058] 71, 71': conventional membrane
element [0059] 81: conventional membrane module [0060] 82, 82':
conventional membrane unit [0061] 83, 83': housing storing membrane
element [0062] 84: upper housing [0063] 85, 85': collecting pipe
[0064] 86, 86': tube for taking filtered water out
BEST MODE FOR CARRYING OUT OF THE INVENTION
[0065] Hereinafter, the invention will be described in detail with
reference to drawings of embodiments of the invention. FIG. 1 is a
schematic perspective view showing one embodiment of a membrane
element of the invention and showing the state before filtering
membranes 11 are attached to the supporting plate 12. FIG. 2 is a
schematic perspective view showing one embodiment of a membrane
module 41 produced by combining a membrane unit 42 using the
membrane element 1 with an air diffuser. FIG. 3 is a schematic top
view showing the top face of the membrane unit 41.
[0066] The membrane element 1 shown in FIG. 1 is configured by
installing the filtering membranes 11 on both surfaces of the
plate-like supporting plate 12, and spacer parts 13 for keeping the
prescribed distance to an adjacent membrane element are formed in
both right and left sides (end parts in the horizontal direction of
the membrane elements) of the supporting plate 12. The spacer parts
13 are thicker than the supporting plate and are extended upward
higher than the upper end part of the supporting plate (the upward
extended parts are called as extended parts 15).
[0067] A nozzle-like filtered water outlet 17 is at the upper end
part of the supporting plate 12. On the other hand, sheet-like
filtering membranes 11 are installed on both front and rear
surfaces of the supporting plate 12, and a filtered water flowing
space (filtered water chamber) is formed in the inside of the
filtering membranes. The filtered water outlet 17 is connected to
the filtered water chamber between the filtering membranes 11 and
the supporting plate 12 via a channel 18. The filtered water
flowing into the filtered water chamber after filtered from the
outside of the filtering membranes 11 is discharged out of the
filtered water outlet 17 via the channel 18.
[0068] The supporting plate 12 is not particularly limited as long
as it is an approximately flat plate-like one. A material for that
is not particularly limited as long as it is a material having
toughness equivalent to a bending elastic modulus of about 300 MPa
according to ASTM testing method D790 (2003); however, metals such
as stainless steels, resins such as acrylonitrile-butadiene-styrene
rubber (ABS resin) and vinyl chloride, composite materials such as
fiber-reinforced resin (FRP), and other materials may be properly
selected and used.
[0069] The spacer parts 13 are thick parts installed at both side
parts of the supporting plate 12, and as shown in FIG. 3, raw water
channels 51 are formed between filtering membranes of the adjacent
membrane elements 1 by these spacer parts 13. Therefore, the
thickness of the spacer parts 13 is set in accordance with the
width of the raw water channels 51. The width of the raw water
channels 51 is not particularly limited; however, it is preferably
set to adjust the flow speed of the raw water flowing in the raw
water channels 51 to be 0.1 to 1.5 m/s.
[0070] In the spacer parts 13, through bolt insertion holes 14 are
formed. As shown in FIG. 2 and FIG. 3, a plurality of the membrane
elements 1 are fastened and fixed by inserting through bolts 46 in
the through bolt insertion holes 14 to keep the raw water channels
51 between the respective elements constant and uniform gas-liquid
mixing flow can be led to the spaces between respective membrane
elements. Further, since the spacer parts of adjacent membrane
elements are firmly fastened, even if pulsations are generated due
to high speed gas-liquid mixing flow, wear of the spacer parts 13
and damage of the supporting plate 12 can be prevented.
[0071] The shape of the through bolt insertion holes 14 being
formed in the spacer parts 13 is not particularly limited and may
be determined corresponding to the fastening force required for the
spacer parts. However, as shown in FIG. 1, if they are made to be
U-shape holes opened to the side face of the membrane elements and
penetrating form the front surface to the rear surfaces of the
membrane elements, through bolts 46 can be inserted into the
layered membrane elements from the sides and thus the work is made
easy and accordingly, it is preferable. Further, it is preferable
that the depth of the U-shape is equal to or more than the diameter
of the through bolts 46 and the through bolts 46 be entirely put in
the U-shape holes. The depth of the U-shape is a length in the
horizontal direction and in the plane direction of the membrane
elements and is the length between the most projected point and the
most recessed point in the spacer parts, and it is shown as L1 in
FIG. 1.
[0072] Further, the number and the size of the through bolt
insertion holes 14 may be also determined depending on the
fastening force required for the spacer parts. The fastening force
required for the spacer parts is, for example, a stress of 1
kg/cm.sup.2 (9.807.times.10.sup.4 Pa) or higher, and it is
preferable to determine it together with the specification of the
through bolts 46 so as to give the fastening stress. For example,
in the case where through bolts 46 of M12 to M16 (made of SUS 304)
are used, it is preferable to form through bolt insertion holes 14
with a diameter (circular) larger than that of bolts by 0.5 to 3 mm
at 100 to 1000 mm pitches in both spacer parts.
[0073] In FIGS. 1 to 3, the width of the spacer parts 13 is even in
the longitudinal direction (vertical direction at the time of use)
of the membrane elements; however a form in which the width is made
uneven is also preferably usable. As shown with L2 in FIG. 1, the
width of the spacer parts means the length of the portion excluding
the through bolt insertion holes 14 in the horizontal direction and
in the membrane element plane direction.
[0074] Further, in the case where the load by the gas-liquid mixing
flow is very high and the fastening force for the spacer parts has
to be increased more, it is supposed to employ methods of
increasing the number of the through bolts or widening the diameter
of the through bolts; however in both cases, disadvantageous
phenomena would be caused. In the case of increasing the number of
the through bolts, there occur a problem of cost increase for the
through bolts and a problem of complication in the assembling a
membrane unit 42. In the case of widening the diameter of the
through bolts to increase the fastening force, there also occur a
problem that the cost is increased for the supporting plate since
the width of the spacer parts has to be wide depending on the
diameter of the bolts and a problem that it becomes difficult to
evenly fasten the respective parts of the spacer parts since the
area of the parts to be brought into contact with the adjacent
membrane elements is widened.
[0075] Therefore, in order to solve these problems, it is also
preferable to form ribs 23 intermittently at the outside parts of
the spacer parts 13 as shown in the membrane element 1 shown in
FIG. 4 and to form the through bolt insertion holes 14 in the ribs
23. The ribs 23 may be produced integrally from the same material
as that of other portions of the spacer parts 13. According to such
a configuration, the fastening force can be maintained by inserting
through bolts with a desired diameter and the area of the spacer
parts can be narrowed, and thus the spacer parts can be evenly
fastened to one another.
[0076] Further, it is also preferable to form projection parts 21
for fitting and reception parts 22 for fitting it in the spacer
parts 13 as shown in the cross-sectional view of FIG. 5 so as to
easily position at the time of arranging a plurality of membrane
elements. The positioning of the through bolt insertion holes 14 is
thus made easy and through bolts 46 can be easily inserted into a
plurality of layered membrane elements.
[0077] The extended parts 15 may have a structure formed simply by
extending the spacer parts 13 upward higher than the upper end
parts of the membrane elements 1 as shown in FIG. 1 or may be
formed to have a shape different from other portions of the spacer
parts 13 as shown in FIG. 6. In the embodiment shown in FIG. 6, the
channel parts 31 are formed in the extended parts 15 corresponding
to the upper parts of the spacer parts 13. In this case, the
channel parts 31 have through holes 32 for forming water collecting
pipes of filtered water in the approximately center in the
thickness direction (in the arrangement direction of the membrane
elements at the time of use) and are configured in such a manner
that filtered water can flow from the filtered water chambers to
the through holes 32 for forming a water collecting pipe via
collecting grooves 16 and channels 18 formed at the supporting
plates 12. The through holes 32 for forming the water collecting
pipe form a continuous water collecting pipe when a membrane unit
is assembled by arranging the membrane elements in such a manner
that the channel parts thereof are brought into contact with one
another as shown in FIG. 7.
[0078] The entire circumferential rim parts of the filtering
membrane 11 are liquid-tightly fixed to the supporting plates 12 by
means such as melt deposition, fusion, adhesion, or the like to
partition the filtering membranes 11 in which the outer face is raw
water side and the inner face is filtered water side. The filtering
membranes 11 are not particularly limited, in the case of
solid-liquid separation of activated-sludge water, a flat membrane
type filtering membrane with a pore diameter determining the
filtration capability of the filtering membranes 11 in a range of
0.01 to 20 .mu.m is preferable.
[0079] The membrane elements 1 composed of the above-mentioned
parts are assembled to form membrane units shown in, for example,
FIGS. 2, 3, 7, and 8. FIG. 2 is a schematic perspective view
showing one embodiment of a membrane module produced by combining a
membrane unit using the membrane element shown in FIG. 1 with an
air diffuser, FIG. 3 is a schematic top view thereof, FIG. 7 is a
schematic perspective view showing one embodiment of a membrane
module produced by combining a membrane unit using the membrane
elements shown in FIG. 6 with an air diffuser, and FIG. 8 is a
schematic drawing showing an integration method of the membrane
elements 1 and the seal panels 45.
[0080] The membrane units 42 of the invention shown FIGS. 2 and 7
are basically composed of a plurality of the membrane elements 1 as
described above and the seal panels 45 installed to the outermost
parts of these membrane elements 1, and through bolts 46 are
optionally employed for integration. Herein, the outermost parts of
a plurality of the membrane elements 1 mean both end parts in the
membrane element arrangement direction.
[0081] The seal panels 45 are plate-like ones for covering the
outermost parts of the arranged membrane elements 1, and in the
case of integration by through bolts, through bolt insertion holes
52 are formed. Since the respective raw water channels 51 between
membrane elements 1 are preferable to have approximately uniform
width, it is preferable to install spacer parts to the both right
and left side parts (the side brought into contact with the spacer
parts 13 of the membrane elements) of the inner side faces of the
seal panels 45 so as to form the raw water channels 51 with
approximately same width between the membrane elements as shown in
FIG. 3 also. A material for the seal panel 45 is not particularly
limited and same materials as those of the supporting plates 12 can
be properly selected.
[0082] The through bolts 46 are not particularly limited as long as
they can integrate and fix the seal panels 45 and a plurality of
membrane elements 1 by penetration. The number of the through bolts
and the bolt diameter may be properly set depending on the
fastening force and weight of the membrane unit 42. At the time of
fixation of the through bolts 46, it is preferable to fix them by
setting nuts 50 at both ends. In the case of layering a plurality
of membrane elements 1, while the spacer parts 13 of adjacent
membrane elements are brought into contact with one another, the
membrane elements are arranged, and in this case, the extended
parts 15 are brought into contact with one another. Accordingly,
the extended parts 15 of the spacer parts 13 form walls at the
upper and two opposed side faces of the membrane unit. Further, the
seal panels 45 are layered at the outermost parts of the membrane
elements 1, and walls are formed at remaining two opposed side
faces of the membrane unit by the upper parts of the seal panels 45
by using those having a shape covering the extended parts 15 for
the seal panels 45. That is, a frame body 48 surrounding the space
above the filtering membranes is formed by the extended parts 15
and the seal panels 45, and by the frame body 48, a space part 49
above the membrane elements 1 can be reliably retained.
Accordingly, the speed of the gas-liquid mixing flow can be
increased without installing upper housing, being an additional
part, above the membrane elements.
[0083] In the case of using membrane elements having spacer parts
13 having the projection parts 21 for fitting and reception parts
22 for fitting it as shown in FIG. 5, a work of fitting the
projection parts 21 for fitting of one membrane element with the
reception parts 22 for fitting of an adjacent membrane element is
simply repeated. Accordingly, the positioning of the through bolt
insertion holes 14 can be carried out and the work for inserting
the through bolts 46 to be carried out thereafter is made
simple.
[0084] The membrane elements 1 and the seal panels 45 are united by
the through bolts 46. At the time of uniting them, through bolts 46
are fitted into the through bolt insertion holes 14 of a plurality
of the arranged membrane elements 1 from the side and then inserted
into hole parts 52 of one seal panel 45. Thereafter, the membrane
elements are moved to bring the spacer parts into contact with one
another. After a prescribed number of membrane elements are
arranged, the through bolts 46 are inserted into hole parts 52 of
the other seal panel 45 and fixed by nuts 50. In such a manner, the
membrane unit 42 can be assembled.
[0085] In the case where the through bolt insertion holes 14 are
opened to the side face, the assembly space necessary for inserting
the through bolts 46 into a plurality of the membrane elements 1
can be narrowed as compared with that in the case where the holes
have a simple hole shape not opened to the side face, and further
the through bolts 46 can be easily inserted. The more the number of
the membrane elements 1 is increased, the more effect of saving the
space is significant. In addition, the holes to be formed in the
seal panels 45 are made simple circular holes not opened to the
side, so that the through bolts 46 can be prevented from dropping
by tremors during the operation.
[0086] At the time of uniting the membrane elements 1 and the seal
panels 45, as shown in FIG. 8, after a plurality of membrane
elements 1 are arranged in approximately vertical state to keep the
surfaces of the filtering membranes 1 vertically, the through bolts
46 are fitted in the U-shape parts from the side, and thereafter,
the through bolts 46 may be inserted into the hole parts 52 of the
seal panels 45 to unit the membrane elements simultaneously with
installation of them. Further, while one seal panel 45 is laid on a
floor face, a plurality of membrane elements 1 are layered thereon
and the through bolts 46 are fitted in the U-shape parts 14 and the
hole parts 52 from the side, and the other seal panel 45 is finally
layered on the uppermost membrane element 1 to unit them (not
shown). In any case, the through bolts 46 can be inserted into the
U-shape part 14 from a narrow space in the side of the membrane
elements.
[0087] Further, in the case of the membrane unit as shown in FIG.
7, the channel parts 31 having through holes 32 for forming a water
collecting pipe are brought into contact with one another to
communicate the through holes 32 and form the water collecting
pipe, and the water collecting pipe is provided with a function as
a water collecting conduit for collecting the filtered water coming
out of a plurality of the membrane elements 1. At the time of
bringing the channel parts 31 of the spacer parts, the adjacent
channel parts 31 may be stuck and sealed; however it is more
preferable to insert O-rings, gaskets, liquid-type gaskets or the
like between the respectively channel parts 31 and to fasten and
seal them with through bolts 46. Further, water collecting caps 53
for taking collected filtered water out are preferably installed at
positions corresponding to the channel parts 31 in the both outmost
parts of a plurality of membrane elements 1. Accordingly,
collecting pipes 85 and tubes 86, as shown in FIG. 12, which are
required for prior arts are no more needed, and installation of the
membrane module 41 can be advantageously carried out in a space
saving manner. Further, at the time of operation, due to the air
discharged from the air diffuser 44, upward gas-liquid mixing flow
is generated in the membrane module and on the other hand, downward
flow of wastewater is generated in the outside of the membrane
module. In the case of the configuration as shown in FIG. 7, since
inhibition of the upward flow by a tube or inhibition of the
downward flow by a collecting pipe does not occur, even flow in
right and left can be advantageously generated without decreasing
the speed of the gas-liquid mixing flow.
[0088] The membrane unit 42 assembled in such a manner is used as a
membrane module 41 by installing the air diffuser 44 for jetting
air under the unit. The air diffuser 44 may be fixed in a stand 43
mounting the membrane unit 42 thereon as shown in FIG. 2 and FIG.
7, or may be installed separately. The installation and
configuration of the diffuser 44 are not also particularly limited;
the installation may be proper to evenly send air to a plurality of
the membrane elements and the configuration may be proper to have
air diffusion holes. As one example, a plurality of pipes are
installed under the membrane elements 1 and air diffusion holes are
formed at constant intervals in the upper faces or lower faces of
the pipes. The number and the size of the holes as the air
diffusion holes are not particularly limited and may be properly
set depending on the air amount.
[0089] As shown in FIG. 2, it is also preferable to set a lower
frame body 47 under the membrane unit 42 between the stand 43 and
the membrane unit. Installation stability of the membrane unit 42
can be increased by mounting the membrane unit 42 on the lower
frame body 47 and then on the stand 43. That is, in the case where
the lower frame body 47 is installed, when the membrane unit 42 is
hung up, a problem that the arranged membrane elements are
displaces or the through bolts 46 are loosened can be solved. The
lower frame body 47 is preferable to have a structure to be fixed
by bolts under the seal panels 45. Further, the lower frame body 47
is preferable to have a shape having an open space just under the
membrane elements not so as to inhibit the raw water channel
51.
[0090] As shown in FIG. 9, a plurality of the membrane units of the
invention maybe layered vertically in multi-decks. In this case,
the space part 49 surrounded with the frame body 48 composed of the
extended parts 15 of the spacer parts 13 and the seal panels 45 is
formed on the upper part of each membrane unit 42. That is, as
shown in FIG. 10 (cross-sectional view of FIG. 9), without
installation of a conventionally used upper housing 84 (see FIG.
13), the space part 49 can be formed between an upper and a lower
membrane units. In the case of a conventional module 81 of
multi-deck membrane units as shown in FIG. 13, since the module has
a configuration that the filtered water flowing out of the
lower-deck membrane unit 82 is collected to a collecting pipe 85
via a tube 86, a drilling work for opening a hole for passing the
tube 86 to the upper housing 84 is necessary; however, in the case
of the multi-deck membrane unit structure using the membrane
elements 1 as shown in FIG. 6, such a drilling work is not required
and the installation space for the collecting pipes 85 and 85' (see
FIG. 13) is also no more needed, so that the treatment tank can be
advantageously made compact. In order to increase the height of the
space part above the membrane unit, another housing (not shown) may
be installed between the lower-deck membrane unit and the
upper-deck membrane unit. Even in the case of installing another
housing, the upper housing can be made to have a lower height than
that of a conventional one.
[0091] As shown in FIG. 11, the membrane module 41 is used while
being immersed in a treatment tank 63 storing water 61 to be
treated. The membrane module 41 is immersed in the treatment tank
63 storing the water 61 to be treated, a suction pump 64 for
suctioning the filtered water is connected to the membrane module
41, and a pipe 62 for supplying air is connected to the air
diffuser 44. In FIG. 11, the suction pump 64 is used for taking the
filtered water out of membrane unit 42; however, additionally,
gravity filtration may be carried out using head difference between
the water surface in the treatment tank 63 and the part where
filtered water is taken out.
[0092] In the water treatment apparatus configured in such a
manner, the water 61 to be treated such as wastewater is passed
through the filtering membranes installed in the membrane elements
1 by suctioning force of the pump. In this time, microorganism
particles and suspended solid such as inorganic particles or the
like contained in the water 61 to be treated can be filtered and
remain in the water 61 side. The water passing through the
filtering membranes (filtered water) is taken outside of the
treatment tank 63 from the spaces (filtered water chambers) between
the supporting plates and filtering membranes via the water
collecting pipes and the like. On the other hand, simultaneously
with the membrane filtration, air is jetting from the air diffuser
44 and enters to the raw water channels of the membrane units. The
ascending gas-liquid mixing flow parallel to the membrane faces of
the membrane elements 1 generated by ascending air separates the
filtered matter deposited on the membrane faces and washes the
membrane faces.
INDUSTRIAL APPLICABILITY
[0093] The membrane elements and membrane units of the invention
can be used in the case of water filtration treatment while being
installed in a treatment tank and can be utilized for wastewater
treatment and water purification treatment.
* * * * *